Machine-readable bar codes have become commonplace today, virtually every pre-packaged food product or household product sold in supermarkets having a bar code printed on its package. The bar codes are read by electronic readers at the check out counters. This not only speeds the process of customer check out, but has become a valuable asset in inventory control.
Optical character recognition codes called OCR's are also in wide common usage today. They have the additional advantage of being both machine-readable and human-readable. These types of codes are ideally suitable in the process of automatically locating an article which is one of many similar articles contained in storage files, as for example library stacks.
For years, the accepted state of the art means for supplying digital magnetic tape to data processors and other users was the familiar ten and one half inch reel of ferrous oxide magnetic tape. The development of the IBM 3480 Magnetic Tape Subsystem, which utilizes a recording medium of cromium-dioxide magnetic particles on tape, contained within a compact, easy to handle, cartridge is rapidly making the ten and one half inch tape reels obsolete. Not only is chromium-dioxide magnetic tape technology better than ferrous-oxide tape, but being stored in specially designed cartridges, which are about four by five inches in size, has resulted in substantial space savings for users.
Storage Technology Corp., ( a.k.a. STORAGETEK ) of Louisville, Colorado has developed an automated system for storing, retrieving, driving and then returning cartridges of this type to library stacks. STORAGETEK has very successfully embodied such a system in the 4400 18 Track Cartridge System.
The [Cimmarron] 4400 System employs a scanning robotic pickup system centrally located within a generally circular library stack where the cartridges are stored when not in use. A coding label is located on each cartridge and a camera, for example, a charged couple device, scans the label and feeds the information to a computer. The computer software reads the label prior to instructing the robot to remove the cartridge and mount it on the drive mechanism. After the cartridge is no longer needed, the robot is instructed by the softwear to dismount the cartridge from the drive and return it to its appropriate position in the library stack.
The entire function therefore, is dependent on the information contained on the label. There is considerable value in the redundancy of the label having two or more codes which are machine-readable, human-readable and combinations of both. It is obvious that if the label were only human-readable it could not be employed in an automated system relying on a camera-reader. If the label were only machine-readable and a portion of the label were missing or obliterated the automated system could not work as efficiently.
The redundancy of two identical machine-readable codes offers the protection of a backup system within the total automatic system for assuring that the proper cartridge has been selected.
Additionally, a label having one or more human-readable messages which are identical to the machine-readable messages assures total back-up if the automated system is "down".
It was with this background in mind, the present invention was conceived.